The international trade of greater rhea is monitored, and they are often found in protected areas. To protect the wild population, there are a number of greater rhea farms which have been set up in recent years to cope with the supply and demand of rhea products.
The rhea will often feed with other animals, taking advantage of them to find food and for protection. They can be seen feeding alongside herds of pampas deer, guanacos, and domestic livestock.
Life span Around 15 years in the wild, can live longer in captivity
They are a very social animal, often forming mixed herds to forage with pampas deer, guanacos, and domestic animals. This allows them to find food sources more readily, and gives an element of protection and safety in numbers.
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Sitting- Knee and heel joints flex completely, making the tibia and tarsi parallel. The neck may extend straight out on the ground or fold into an S-curve.
Rhea feed mainly on plant matter, such as roots, leaves, fruits, and seeds. They will also eat insects, lizards, frogs, small birds, and even snakes.
The greater rhea is a silent bird except during mating season, when they make low booming noises, and as chicks, when they give a mournful whistle. During the non-breeding season they will form flocks of between 10 and 100 birds. When in flocks, they tend to be less vigilant, but the males can get aggressive towards other males. When chased they will flee in a zigzag pattern, alternately raising one wing then the other. These flocks break up in the winter in time for breeding season.
They are often seen as pests by farmer due to their supposed habit of eating agricultural crops, and are often killed for this reason; however there is strong evidence that the rhea play a positive role in agriculture, eating the weeds and pest species of plant, not the crops.
In agricultural areas Greater Rheas eat mostly alfalfa and wild dicots, with no preference for grasses. Rheas consume higher proportions of alfalfa in the winter, when the resource is too short to be used by cattle, and thus pose no competition for cattle grazing opportunities (Martella et al. 1996).
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R. americana americana (Linnaeus, 1758) R. a. intermidia (Rotschild & Chubb, 1914) R. a. nobilis (Brodkorb, 1939) R. a. araneipes (Brodkorb, 1938) R. a. albescens (Arribálzaga & Holmberg, 1878)
Populations of rhea are decreasing greatly in South America. Although the adults have no predators the young may be taken by dogs and other terrestrial predators. The adults suffer from hunting for various uses. The eggs and meat are taken for food, and often as food for domestic dogs. The feathers are used to make feather dusters, and the skin is used for leather.
Both sexes are more vigilant in higher vegetation (Martella et al. 1995).
A rhea will defecate most often while feeding and occasionally while drinking.
Text account compilersSymes, A., Benstead, P., Capper, D., Symes, A., Sharpe, C J
The greater rhea is the largest bird found on the American continent.
Greater rheas are opportunistic eaters. They enjoy plants, fruits, and seeds but also eat insects, lizards, birds, and other small game. Rheas have a taste for agricultural crops, which earns them the ire of many South American farmers. As more open grasslands are converted to farmland, this problem grows.
Greater rheas are polygamous, so males have many different mates. Females lay their eggs—one every other day for a week or ten days—in a ground nest of the male's design. Several females deposit their eggs in the same nest, which may hold 50 eggs or more.
Proyecto Ñandúes (in Spanish): http://www.efn.uncor.edu/departamentos/cza/nandues/nandues.htm
These animals have also been seen swallowing small pebbles; this is to help grind up the food in their gizzard (a muscular pouch behind the stomach), before it is properly digested.
Greater rheas have a fluffy, tattered-looking plumage, that is gray or brown, with high individual variation, The head, neck, rump, and thighs are feathered. In general, males are darker than females. Even in the wild—particularly in Argentina—leucistic individuals (with white body plumage and blue eyes) as well as albinos occur. Hatchling greater rheas are grey with dark lengthwise stripes.
Like some other birds, rhea will swallow pebbles to help digest their food.
Observed predation on adult wild rheas occurred during harem formation and courthsip (July-August). Reduced vigilance during the breeding season may put rheas at greater risk of predation during this time.
The male will rear the young, taking care of them for up to four months. They will shelter under his wings when threatened, or when too hot or cold. The females play no part in the rearing of the young. The juveniles will stay together, even after they leave their parent, until they reach sexual maturity at the age of around two years.
Eggs are elliptical and shiny in texture. Fresh eggs are golden in color, but become white after being exposed for 5-6 days to the sun (Sick 1993). The mean clutch size of nests at one site in Argentina was 26.1 (Bruning 1974). Average mass of the egg is 605 g (Mato Grosso; Sick 1993).
Parker, T. A.; Stotz, D. F.; Fitzpatrick, J. W. 1996. Ecological and distributional databases. In: Stotz, D.F.; Fitzpatrick, J.W.; Parker, T.A.; Moskovits, D.K. (ed.), Neotropical bird ecology and conservation, pp. 113-436. University of Chicago Press, Chicago.
Our rhea will dig their own shallow scrapes into the ground to sleep and sunbathe in, just as in the wild. They will also nest, and breed naturally.
Standing- One foot stands about twelve inches behind the other. One leg angles slightly, supporting less weight than the other, held vertically.
Rheas are subject to high predation throughout their lives.
During sexual or agonistic encounters,a rhea runs crouching, moving the wings and neck, and ruffling the plumage. Captive rheas running to be fed by spectators hold the neck vertically, wings only slightly raised, with no ruffling of plumage (Raikow 1968). Running increases body temperature and the rhea must manage its body temperature by storing heat (Taylor 1971).
Just as in the wild they will feed alongside other species, in the wild this will be animals such as pampas deer, guanacos, and domestic livestock. Here at Woburn they live with our large group of wallaby, who they happily form a mixed herd with when foraging, feeding, and even sleeping.
Rhea are generally silent, except for the male, performing a low ‘grunt’ as part of his courtship display, and the young chicks, who will call to their parents when young. Adults, especially breeding males, may ‘hiss’ when protecting the nest of young or when feeling threatened. They instead communicate mainly through body language, using their wings for threat displays and courtship displays.
Canevari, M. 1991. Nueva guia de las aves Argentinas. FundaciÃ³n Acindar, Buenos Aires.
Conservation and reintroduction plans should consider the cougar a limiting factor of wild rhea populations, and address the currently unstudied effect of the increasing six-banded armadillo population on nesting success (Mercolli and Yanosky 2001).
The greater rhea is the largest of all South American birds and is related to ostriches and emus. These flightless birds use their long, powerful legs to outrun trouble. Although their large wings are useless for flight, they are used for balance and for changing direction as the bird runs.
The greater rhea typically inhabits tall grassland, open woodland and wooded savanna, such as the pampas, cerrado, and chaco woodland habitats of South America. The species can also be found in cultivated fields when the crop height is low (11), and occurs at elevations of up to 2,000 metres (2) (3) (12).
ReferencesBellis, L, Martella M. B. and Navarro J. L. 2004. Habitat use by wild and captive-reared greater rheas Rhea americana in agricultural landscapes in Argentina. Oryx 38(3): 304-310.
An adult will weigh between 20 to 40kg, and be up to 150cm tall. The juvenile bird will be fully grown by the age of six months.
Rheas are suited for life in wide plains, using long, strong legs to cover distance quickly. The rhea generally ambles at a leisurely pace, running only during social activities (Raikow 1968). The head moves back and forth slightly along the sagittal plane as the rhea walks, a common movement among birds that may give mechanical assistance to walking and aid in visual fixation on surroundings (Daanje 1950).